Lretrnfl11oclockthicknessoct
This test measures the thickness of the retinal nerve fiber layer at the 11 o'clock position of the left eye using optical coherence tomography (OCT).
{"A non-invasive eye imaging test using light waves","Measures retinal nerve fiber layer thickness to detect glaucoma damage","The 11 o'clock position corresponds to the nasal side of the optic nerve","Results help doctors monitor eye health and disease progression","Painless procedure taking only a few minutes"}
Key facts at a glance
- LOINC
- 86303-5
- Short code
- RNFL-OCT-11-L
- Synonyms
- L ret RNFL 11 o'clock thickness OCT
- Category
- cardiac
- Sample
- serum
- Container
- N/A - Imaging study, no specimen collection required
- Units
- N/A
- Ref low
- 70
- Ref high
- 140
- Critical range
- — – 10000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- Optical Coherence Tomography (OCT)
- CPT
- 92133
- SNOMED
- 371632009
- Specimen volume
- N/A - Non-invasive imaging test
- Stability
- N/A - Imaging test performed immediately
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 1–24 hours
- Order
- routine
What is this test?
The Left Retina Retinal Nerve Fiber Layer (RNFL) Clock Hour 11 Thickness test uses Optical Coherence Tomography (OCT), a non-invasive imaging technique that uses light waves to create detailed cross-sectional images of the retina. Specifically, it measures the thickness of the nerve fiber layer at the 11 o'clock position on the optic nerve head of your left eye.
How is the test performed?
During the test, you will sit in front of the OCT machine and place your chin on a support while looking at a target. The device scans your eye without touching it, using light beams to capture detailed images. The entire process takes only a few minutes and is completely painless. No eye drops or preparation are typically required.
What does the test show?
The test provides a precise measurement of the retinal nerve fiber layer thickness at a specific location (clock hour 11). This location corresponds to the nasal portion of the optic nerve. Thinner than normal measurements may indicate damage to the optic nerve, often associated with conditions like glaucoma.
Reference range
Reference range varies by age and optic disc size; typically 70-140 micrometers for clock hour 11 sector in healthy adultsN/A
Patient should remove contact lenses if applicable. Pupils may need dilation for optimal imaging. Avoid eye drops that may affect pupil size unless specifically instructed.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
Do I need to fast before this test?
Is the test painful?
How long does the test take?
When will I get my results?
How often should this test be repeated?
Sources
- 1
- 2
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy